1. Field of the Invention
The present invention relates in general to a backplane configuration for use in electronic crate systems, especially in electronic crate standard systems. In particular, the invention relates to a backplane configuration for use in electronic crate systems comprising a first backplane and a second backplane, wherein the first backplane can be a standard backplane, and the second backplane can be a special purpose backplane. For example, both backplanes can be configured for different types of signals which different types of signals can be analog signals and digital signals, or high-precision low-noise synchronous signal and high-speed (or ultrafast) asynchronous signals. In a special application, one of the backplanes is an RTM-backplane (RTM=Rear Transition Module), and the other backplane is AMC-backplane (AMC=Advanced Mezzanine Card). The configuration of two backplanes (as defined above) according to the invention is referred hereafter as “backplane configuration” or “high-frequency backplane configuration” when the high-frequency or high-speed signals are used. In case the first backplane is an AMC-backplane (or any other type of standard backplane), and the second backplane is an RTM-backplane, the inventive configuration of these two backplanes for use in electronic crate systems is designated as “RTM-backplane configuration”. By means of the backplane configuration (and the RTM-backplane configuration) of the present invention, the functionality of an electronic crate (standard) system can be improved and extended by providing, for example, ultra-stable high frequency interconnections and high precision clock interconnections together with a high performance analog power supply for the modules coupled to the respective backplanes, for example RTM modules in case of the RTM-backplane.
Electronic crate systems are preferably used for applications where multichannel RF front-ends or analog signal conditioning modules are used together with powerful digital signal processing and data computation systems in a common crate system. In a preferred embodiment, the backplane configuration (for example the RTM-backplane configuration) of the present invention is introduced to the MTCA.4 (Micro Telecommunication Computing Architecture) crate standard system without affecting standard functionality of this crate system. However, the backplane configuration or RTM-backplane configuration of the present invention can also be used with other crate systems or crate standard systems.
2. Discussion of the Prior Art
Modular systems and modular crate systems are typically used in communication networks, computer networks or other data processing networks where reliability, high-frequency data processing and high-speed data transmission are important factors. A key component of such a modular system is the modular platform. Such a modular platform usually includes a backplane that is provided with various types of interconnections. These interconnections may include several slots, interfaces and/or IO-connections for receiving and electrically coupling several modules that provide additional functionality to the modular system. These modules may include front accessible modules and rear transition modules such as AMC modules and RTM modules, or, more general standard modules and special purpose modules configured for processing different types of signals, such as high-speed asynchronous signals and high-precision low-noise synchronous signals.
Nowadays, crate standard systems provide powerful computing platforms with large flexibility of configuration and high reliability features. As an example, in late 2011 the MTCA.4 specification released by PICMG® defined the Rear Transition Module (RTM) for the MTCA crate system. These RTM modules are active and hot-swappable. The MTCA crate system includes rear RTM modules and front AMC (Advanced Mezzanine Card) modules. The rear RTM modules are adapted to be directly connected to front AMC modules by so called Zone3 connectors providing for RTM power supply, IPMI-based management, hot-swap signals and user defined IO signals. It was commonly approved that digital subsystems can occupy standard front AMC modules, and the analog applications can be implemented on rear RTM modules. By such layout physical separation of analog and digital domains is achieved and higher system performance can be assured.
The biggest problem of such crate systems is the provision of high-frequency interconnections between the RTM modules and the quality of power supply voltage derived from the digital AMC modules. Up to now, high precision high frequency signals and low jitter clocks have to share a single backplane (the standard AMC-backplane) in the crate standard systems with highly asynchronous digital signals and communications buses (e.g. PCIe, Ethernet, SATA etc.) with data transfer rates of one (1) Gbps to forty (40) Gbps, which complicates and limits the signal-integrity and therefore the performance of the existing crate standards. In addition, external RTM interconnections realized with cables significantly reduces the reliability, maintainability and performance of entire crate system.